Scaling out a hybrid cloud storage service

ABSTRACT

Software and resources, pre-deployed in accordance with a disaster recovery policy, are placed in a standby state to provide rapid disaster recovery in a cloud storage environment. When a disaster recovery situation is detected, (for example a loss of access to primary data), the pre-deployed resources are immediately activated according to the disaster recovery policy to provision and re-configure adequate resources and rapidly restore access to the data (such as restoring data from cloud backup storage). A disaster recovery situation may involve, for example, loss of hardware availability, network bandwidth interruption, or a sudden and large unforeseen jump in storage retrieval request volume (for example a recall storm).

BACKGROUND OF THE INVENTION

The present invention relates generally to the field of cloud storage,and more specifically to disaster recovery solutions in a cloudenvironment.

A cloud computing environment provides shared computer processingresources on demand, including data storage and backup. In somescenarios, an enterprise employs cloud storage backup to protectcritical on-site data. In case some of the on-site data becomesinaccessible, for example due to a hardware or networking problem, theenterprise can recover the data from the cloud backup.

Some data storage systems, including cloud storage systems implement astorage tiering strategy, whereby data that is accessed frequently isplaced on a fast storage tier, such as solid state drives, while datathat is accessed less frequently is placed on a slower storage tier suchas hard drives, optical drives, and/or tape drives.

SUMMARY

According to an aspect of the present invention, there is a method,computer program product and/or system that performs the followingoperations (not necessarily in the following order): receiving adisaster recovery policy with respect to a first storage system;pre-deploying resources according to the disaster recovery policy, toprovide pre-deployed resources; receiving information indicative of adisaster recovery situation with respect to a first set of data storedon the first storage system; and activating the pre-deployed resourcesaccording to the disaster recovery policy.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a functional block diagram depicting a computing environmentin accordance with at least one embodiment of the present invention;

FIG. 2 is a disaster handling method in accordance with at least oneembodiment of the present invention;

FIG. 3 is a block diagram showing a machine logic (for example,software) portion of at least one embodiment of the present invention;and

FIG. 4 is a block diagram depicting components of a computer, inaccordance with at least one embodiment of the present invention.

DETAILED DESCRIPTION

Some embodiments of the present invention pre-define policies forhandling disaster recovery (DR) situations in a cloud storageenvironment. Software and resources are pre-deployed and standing by.When a DR situation is detected, for example causing a loss of access toprimary data (the protected data), the pre-deployed resources areimmediately activated to provision and re-configure adequate resourcesto rapidly restore access to the data, (such as restoring the protecteddata from cloud backup storage) in an optimum fashion. A DR situationcan involve loss of hardware availability, network bandwidthinterruption (disaster), or a sudden and large unforeseen jump instorage retrieval request volume (recall storm).

This Detailed Description section is divided into the followingsub-sections: (i) The Hardware and Software Environment; (ii) ExampleEmbodiment; (iii) Further Comments and/or Embodiments; and (iv)Definitions.

I. THE HARDWARE AND SOFTWARE ENVIRONMENT

FIG. 1 is a functional block diagram depicting a computing environment100 in accordance with an embodiment of the present invention. Computingenvironment 100 includes: client computer system 110; user interface120; cloud storage system 130, storage tier 140; and network 150. Clientcomputer system 110 can be any of a desktop computer, a laptop computer,a specialized computer server, or any other computer system known in theart. In some embodiments, client computer system 110 represents acomputer system utilizing clustered computers and components to act as asingle pool of seamless resources when accessed through network 150. Ingeneral, client computer system 110 is representative of any electronicdevice, or combination of electronic devices, capable of executingmachine-readable program instructions, as described in greater detailwith regard to FIG. 4.

II. EXAMPLE EMBODIMENT

FIG. 2 shows flowchart 200 depicting a method according to the presentinvention. FIG. 3 shows auto-scaling program 300 for performing at leastsome of the method operations of flowchart 200. This method andassociated software will now be discussed, over the course of thefollowing paragraphs, with extensive reference to FIG. 2 (for the methodoperation blocks) and FIG. 3 (for the software blocks).

Processing begins at operation S210, where policy module 310 ofauto-scaling program 300 receives and stores disaster recovery policyinformation. In some embodiments of the present invention, the disasterrecovery policy information is input by a user (for example, a storagesystem administrator, not shown in the Figures). Alternatively, thepolicy information may be a pre-defined set of storage system defaults,or a combination of system defaults and user input.

The disaster recovery policy includes information that identifies a setof nodes in an existing cluster that are available to be used by agateway in a “disaster recovery mode”. Similarly, a set of nodes isidentified that are available to be used in a “recall storm mode”. Insome embodiments of the present invention, these nodes have the storagetiering service pre-installed on them so that bring-up can be immediatewith very little overhead. Moreover, in some embodiments of the presentinvention, if cloud services are available, the disaster recovery policyidentifies a number of nodes that can be provisioned dynamically on thecloud such that the nodes are provided on demand when needed.

Processing proceeds at operation S212 where protected resourcemonitoring module 330, of auto-scaling program 300, detects a change inthe configuration of the protected data. A configuration change mayencompass changes to: (i) the size (data capacity) of the protecteddata; (ii) the tiering structure of the protected data; (iii) thephysical location(s) of the data; (iv) the redundancy of the data, etc.,to name a few examples.

Processing proceeds at operation S214 where in response to detecting (inoperation S212 above) the protected resource configuration change,policy module 310 of auto-scaling program 300 automatically modifies thedisaster recovery policy in accordance with the configuration change.For example, if the protected data doubles in size from 100 TB to 200TB, the resources specified in the DR policy to provide the necessarybandwidth may double. If on the other hand the protected data are splitup and distributed between two data centers, the DR policy is modifiedto remain current with that configuration change.

Processing proceeds at operation S220, where event recognition module322, of activation module 320, receives input indicating that a disasterrecovery (DR) situation has developed. The DR situation in general isdefined, in some embodiments of the present invention, as any event thatrequires rapid restoration of a large volume of data from one system toanother (such as from a cloud backup storage system to an on-premisesstorage system) that is sudden, unforeseen, and/or unusual in magnitude.

Processing proceeds at operation S230, where resource provisioningmodule 324, of activation module 320, dynamically provisions resourcesthat were pre-installed in operation S210 above. In the case ofon-premises pre-installed deployment, the resources are all added toexisting node groups so that the cloud storage tiering or sharingservice has the resources at hand to address the DR or RS situation. Insome embodiments of the present invention, the resources are provisionedaccording to the disaster recovery policy plan set up in operation S210above. Once the provisioning is completed, the resources are assigned toexisting node groups.

Processing proceeds at operation S240, where data restoration module 326of auto-scaling program 300, immediately starts appropriate scaling ofresources available for the tiering or sharing service and initiatesdata recall, for example, from cloud storage system 130 to on-premisesstorage system 115 (see FIG. 1)

III. FURTHER COMMENTS AND/OR EMBODIMENTS

The need for resources of a cloud tiering or sharing service, such as atransparent cloud tiering service (which provides a native cloud storagetier, allowing data center administrators to free up on-premises storagecapacity, by moving out cooler data to the cloud storage), can varygreatly. For example, in the course of normal activities a relativelysmall number of nodes can service routine migration and recall needs fora cool or cold storage tier. However, in unusual situations, such as fordisaster recovery wherein very large amounts of data need to be moved ina short period of time, the service needs far larger amounts ofresources. Conventional auto-scaling techniques do not necessarily coverunusual cases effectively, as these techniques tend to be reactive andmetrics oriented.

Some embodiments of the present invention may include one, or more, ofthe following features, characteristics and/or advantages in a criticalsituation such as a disaster recovery or massive data recall situation:(i) solution may be implemented immediately or even predictively; (ii)provides immediate or predictive resource scaling; (iii) solution allowsfor optimal usage of resources in a critical situation; and/or (iv)dynamically scales up cloud tiering or sharing services (such astransparent cloud tiering services) on demand. The core valueproposition of this auto-scaling approach is to recognize that adisaster recovery situation is at hand and immediately start appropriatescaling of resources available for the tiering or sharing service.

In some embodiments of the present invention, initiation of auto-scalingis triggered by one or more of the following events: (i) a completehardware failure, that for example, takes off-line volumes of data whichin turn necessitates recovery of data from remote source(s) (an exampleof disaster recovery (DR) mode); (ii) bringing-up of a new cluster whereinitialization is done indicating that data will be recovered remotely(an example of DR recovery mode); (iii) manual input (for example by anadministrator), or by a script that puts the system into DR recoverymode; and/or (iv) manual input (for example by an administrator), or bya script, that initiates a large recall request (recall storm mode).

Some embodiments of the present invention include a preparation phaseand an activation phase, as will be discussed in the following fewparagraphs.

Preparation Phase:

The storage administrator sets up a physical environment that will meetthe demands of a disaster recovery scenario. Preparation includes (i)hardware planning; (ii) policy setup; (iii) installation; and/or (iv)dynamic provisioning. The demands of a disaster recovery scenario aredynamic. That is, the disaster recovery resources that need to bemarshaled in a DR scenario may change in accordance with changes in thesize and/or configuration of the storage resources (the protected data)that fall within the scope of the disaster recovery policy. As the sizeor configuration of the protected data changes, the DR resourcesspecified in the DR policy are adjusted accordingly.

(i) Hardware Planning:

Hardware planning includes ensuring that sufficient network bandwidthand other resources such as load balancers are available to meet arequired time window. The required time window, in some embodiments ofthe present invention, is a contractual agreement between a client and asupplier, in which the parties agree that a specified amount of data canbe restored within a specified time limit. In some embodiments of thepresent invention, the required time window is a complex set ofrequirements, involving data quantities, access latencies to certainclasses of data during a recovery period, etc. By way of a simpleexample, a client may identify three data categories (cat 1, cat 2 andcat 3) where: (i) 20% of cat 1 data would be required to be restoredwithin 30 seconds of onset of a disaster scenario and the remaining 80%within 1 minute; (ii) cat 2 within 5 minutes; and (iii) cat 3 within 1hour.

(ii) Setting Up Policy:

In some embodiments of the present invention, metadata is kept out oncloud storage. The storage administrator identifies and prioritizeswhich data is to be returned (in a DR or RS scenario) by setting up, inadvance, a disaster recovery policy. The network bandwidth and otherresources that are planned to meet a DR scenario may change as the sizeof the protected data changes over time. The DR policy is dynamicallychanged accordingly, such that it is properly configured to handle a DRscenario at any given time and for any given state (size, configuration,etc.) of the protected data. The DR policy can leverage any, or all ofthe metadata. The policy may specify that the hottest data (data withthe most I/O activity) and critical data sets that have beenpre-identified, are to be the first data recovered, followed by datathat is less hot and not as critical. This allows the storageadministrator to specify data restoration in an optimal order withrespect to recovering from a potential disaster situation. In the caseof a recall storm, similarly an administrator, by way of setting up thepolicy, prioritizes in advance of an extreme event, as to what data isto be recalled—and the order in which the data is to be recalled. Thepolicy may take into account the order in which the data is requested inreal time at the time of the restoration process.

(iii) Installation:

The system administrator, upon installation, identifies a set of nodesin an existing cluster that are available to be used by the gateway for“DR mode” (“disaster recovery mode”). Similarly, a (possibly different)set of nodes is identified that are available to be used for “RS mode”(“recall storm mode”). These nodes can have the tiering servicepre-installed on them so that bring-up is immediate with very littleoverhead.

(iv) Dynamic Provisioning:

Moreover, in some embodiments of the present invention, if cloudservices are available, the administrator identifies a number of nodesthat can be provisioned dynamically on the cloud for such use, such thatthe nodes are provided on demand when needed.

Activation Phase:

On premises: Once an event happens—for example a recall storm (RS)situation or a disaster recovery (DR) situation—embodiments immediatelyenable resources on the pre-installed nodes. In the case of on-premisespre-installed deployment, the resources automatically are all added toexisting node groups so that the cloud storage tiering or sharingservice has the resources at hand to address the DR situation.

With a Cloud Service:

Once an event, such as a recall storm (RS) situation or a disasterrecovery (DR) situation occurs, the resources are automaticallydynamically provisioned according to the plan (including the disasterrecovery policy) set up by the storage administrator during thepreparation phase. Once the provisioning is completed, the resources areassigned to existing node groups. The restore operations are performedin order of priority. In some embodiments, the name-space is the firstthing that is restored so that the namespace is intact and storageservice can begin. Thereafter, transparent recalls are given the highestpriority such that data that is in need of immediate access is recalledfirst, then followed by additional data that is brought back in priorityorder according to the disaster recovery policy.

Scaling out a hybrid cloud storage service provides accelerated disasterrecovery comprising: (i) pre-defining policies to cover extremesituations including disaster recovery; (ii) preinstalling necessarysoftware to allow nodes to operate in different modes and to operate aspart of different node groups during a range of normal conditions and inextreme conditions; (iii) defining which nodes will be used for thedisaster recovery; (iv) pre-defining relationships of clusters withobject storage in the cloud, so a normal cluster can be converted to,for example, a hyperfast disaster recovery system; (v) predefiningassociations and configurations on the remote cloud to enablerepurposing in the event of a disaster; (vi) repurposing existinghardware into different node groups (including repurposing gatewaynodes, object storage nodes and general compute nodes); (vii)predefining service tiering for extreme conditions such as disasterrecovery; (viii) restoring data in the order of priority.

Some embodiments may not have these potential advantages and thesepotential advantages are not necessarily required of all embodiments.

FIG. 4 depicts a block diagram of components of computer 400 inaccordance with an illustrative embodiment of the present invention. Itshould be appreciated that FIG. 4 provides only an illustration of oneimplementation and does not imply any limitations with regard to theenvironments in which different embodiments may be implemented. Manymodifications to the depicted environment may be made.

As depicted, the computer 400 includes communications fabric 402, whichprovides communications between computer processor(s) 404, memory 406,persistent storage 408, communications unit 412, and input/output (110)interface(s) 414. Communications fabric 402 can be implemented with anyarchitecture designed for passing data and/or control informationbetween processors (such as microprocessors, communications and networkprocessors, etc.), system memory, peripheral devices, and any otherhardware components within a system. For example, communications fabric402 can be implemented with one or more buses.

Memory 406 and persistent storage 408 are computer-readable storagemedia. In this embodiment, memory 406 includes random access memory(RAM) 416 and cache memory 418. In general, memory 406 can include anysuitable volatile or non-volatile computer-readable storage media.

One or more programs may be stored in persistent storage 408 for accessand/or execution by one or more of the respective computer processors404 via one or more memories of memory 406. In this embodiment,persistent storage 408 includes a magnetic hard disk drive.Alternatively, or in addition to a magnetic hard disk drive, persistentstorage 408 can include a solid state hard drive, a semiconductorstorage device, read-only memory (ROM), erasable programmable read-onlymemory (EPROM), flash memory, or any other computer-readable storagemedia that is capable of storing program instructions or digitalinformation.

The media used by persistent storage 408 may also be removable. Forexample, a removable hard drive may be used for persistent storage 408.Other examples include optical and magnetic disks, thumb drives, andsmart cards that are inserted into a drive for transfer onto anothercomputer-readable storage medium that is also part of persistent storage408.

Communications unit 412, in these examples, provides for communicationswith other data processing systems or devices. In these examples,communications unit 412 includes one or more network interface cards.Communications unit 412 may provide communications through the use ofeither or both physical and wireless communications links.

I/O interface(s) 414 allows for input and output of data with otherdevices that may be connected to computer 400. For example, I/Ointerface 414 may provide a connection to external devices 420 such as akeyboard, keypad, a touch screen, and/or some other suitable inputdevice. External devices 420 can also include portable computer-readablestorage media such as, for example, thumb drives, portable optical ormagnetic disks, and memory cards. Software and data used to practiceembodiments of the present invention can be stored on such portablecomputer-readable storage media and can be loaded onto persistentstorage 408 via I/O interface(s) 414. I/O interface(s) 414 also connectto a display 422.

Display 422 provides a mechanism to display data to a user and may be,for example, a computer monitor.

The programs described herein are identified based upon the applicationfor which they are implemented in a specific embodiment of theinvention. However, it should be appreciated that any particular programnomenclature herein is used merely for convenience, and thus theinvention should not be limited to use solely in any specificapplication identified and/or implied by such nomenclature.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof code, which comprises one or more executable instructions forimplementing the specified logical function(s). It should also be notedthat, in some alternative implementations, the functions noted in theblock may occur out of the order noted in the figures. For example, twoblocks shown in succession may, in fact, be executed substantiallyconcurrently, or the blocks may sometimes be executed in the reverseorder, depending upon the functionality involved. It will also be notedthat each block of the block diagrams and/or flowchart illustration, andcombinations of blocks in the block diagrams and/or flowchartillustration, can be implemented by special purpose hardware-basedsystems that perform the specified functions or acts, or combinations ofspecial purpose hardware and computer instructions.

The present invention may be a system, a method, and/or a computerprogram product. The computer program product may include a computerreadable storage medium (or media) having computer readable programinstructions thereon for causing a processor to carry out aspects of thepresent invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as Smalltalk, C++ or the like, andconventional procedural programming languages, such as the “C”programming language or similar programming languages. The computerreadable program instructions may execute entirely on the user'scomputer, partly on the user's computer, as a stand-alone softwarepackage, partly on the user's computer and partly on a remote computeror entirely on the remote computer or server. In the latter scenario,the remote computer may be connected to the user's computer through anytype of network, including a local area network (LAN) or a wide areanetwork (WAN), or the connection may be made to an external computer(for example, through the Internet using an Internet Service Provider).In some embodiments, electronic circuitry including, for example,programmable logic circuitry, field-programmable gate arrays (FPGA), orprogrammable logic arrays (PLA) may execute the computer readableprogram instructions by utilizing state information of the computerreadable program instructions to personalize the electronic circuitry,in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the invention.The terminology used herein was chosen to optimal explain the principlesof the embodiment, the practical application or technical improvementover technologies found in the marketplace, or to enable others ofordinary skill in the art to understand the embodiments disclosedherein.

IV. DEFINITIONS

Present invention: should not be taken as an absolute indication thatthe subject matter described by the term “present invention” is coveredby either the claims as they are filed, or by the claims that mayeventually issue after patent prosecution; while the term “presentinvention” is used to help the reader to get a general feel for whichdisclosures herein are believed to potentially be new, thisunderstanding, as indicated by use of the term “present invention,” istentative and provisional and subject to change over the course ofpatent prosecution as relevant information is developed and as theclaims are potentially amended.

Embodiment: see definition of “present invention” above—similar cautionsapply to the term “embodiment.”

and/or: inclusive or; for example, A, B “and/or” C means that at leastone of A or B or C is true and applicable.

Including/include/includes: unless otherwise explicitly noted, means“including but not necessarily limited to.”

User/subscriber: includes, but is not necessarily limited to, thefollowing: (i) a single individual human; (ii) an artificialintelligence entity with sufficient intelligence to act as a user orsubscriber; and/or (iii) a group of related users or subscribers.

Receive/provide/send/input/output/report: unless otherwise explicitlyspecified, these words should not be taken to imply: (i) any particulardegree of directness with respect to the relationship between theirobjects and subjects; and/or (ii) absence of intermediate components,actions and/or things interposed between their objects and subjects.

Without substantial human intervention: a process that occursautomatically (often by operation of machine logic, such as software)with little or no human input; some examples that involve “nosubstantial human intervention” include: (i) computer is performingcomplex processing and a human switches the computer to an alternativepower supply due to an outage of grid power so that processing continuesuninterrupted; (ii) computer is about to perform resource intensiveprocessing, and human confirms that the resource-intensive processingshould indeed be undertaken (in this case, the process of confirmation,considered in isolation, is with substantial human intervention, but theresource intensive processing does not include any substantial humanintervention, notwithstanding the simple yes-no style confirmationrequired to be made by a human); and (iii) using machine logic, acomputer has made a weighty decision (for example, a decision to groundall airplanes in anticipation of bad weather), but, before implementingthe weighty decision the computer must obtain simple yes-no styleconfirmation from a human source.

Automatically: without any human intervention.

Module/Sub-Module: any set of hardware, firmware and/or software thatoperatively works to do some kind of function, without regard to whetherthe module is: (i) in a single local proximity; (ii) distributed over awide area; (iii) in a single proximity within a larger piece of softwarecode; (iv) located within a single piece of software code; (v) locatedin a single storage device, memory or medium; (vi) mechanicallyconnected; (vii) electrically connected; and/or (viii) connected in datacommunication.

Computer: any device with significant data processing and/or machinereadable instruction reading capabilities including, but not limited to:desktop computers, mainframe computers, laptop computers,field-programmable gate array (FPGA) based devices, smart phones,personal digital assistants (PDAs), body-mounted or inserted computers,embedded device style computers, application-specific integrated circuit(ASIC) based devices.

What is claimed is:
 1. A method comprising: receiving a disasterrecovery policy with respect to a first storage system, wherein thedisaster recovery policy comprises the following information: (i)identification of a first set of nodes that are available to be used bya gateway in a disaster recovery mode; and (ii) identification of asecond set of nodes that are available to be used in a recall stormmode; pre-deploying resources according to the disaster recovery policy,to provide pre-deployed resources; receiving information indicative of adisaster recovery situation with respect to a first set of data storedon the first storage system; and activating the pre-deployed resourcesaccording to the disaster recovery policy.
 2. The method of claim 1,further comprising: monitoring the first storage system with respect toa configuration thereof; determining that the first storage systemunderwent a configuration change; and in response to determining thatthe first storage system underwent the configuration change,automatically adjusting the disaster recovery policy in accordance withthe configuration change.
 3. (canceled)
 4. The method of claim 1,further comprising at least one of: pre-deploying the first set ofnodes; pre-deploying the second set of nodes; pre-installing a storagetiering service on the first set of nodes; and pre-installing thestorage tiering service on the second set of nodes.
 5. The method ofclaim 4, wherein activating the pre-deployed resources according to thedisaster recovery policy comprises: automatically adding the first setof nodes to at least one existing node group; automatically restoring aname-space with respect to the first storage system; and initiatingrestoration of the first set of data.
 6. The method of claim 4, whereinactivating the pre-deployed resources according to the disaster recoverypolicy comprises automatically adding the second set of nodes to atleast one existing node group.
 7. The method of claim 4, wherein thepre-deployed resources comprise: network bandwidth sufficient to meet amaximum data recovery time threshold; at least one load balancersufficient to meet the maximum data recovery time threshold; a firststorage tiering service installed on the first set of nodes; and asecond storage tiering service installed on the second set of nodes. 8.A computer program product comprising: one or more computer readablestorage media and program instructions stored on the one or morecomputer readable storage media, the program instructions comprisinginstructions to perform: receiving a disaster recovery policy withrespect to a first storage system, wherein the disaster recovery policycomprises the following information: (i) identification of a first setof nodes that are available to be used by a gateway in a disasterrecovery mode; and (ii) identification of a second set of nodes that areavailable to be used in a recall storm mode; pre-deploying resourcesaccording to the disaster recovery policy, to provide pre-deployedresources; receiving information indicative of a disaster recoverysituation with respect to a first set of data stored on the firststorage system; and activating the pre-deployed resources according tothe disaster recovery policy.
 9. The computer program product of claim8, further comprising program instructions to perform: monitoring thefirst storage system with respect to a configuration thereof;determining that the first storage system underwent a configurationchange; and in response to determining that the first storage systemunderwent the configuration change, automatically adjusting the disasterrecovery policy in accordance with the configuration change. 10.(canceled)
 11. The computer program product of claim 8, furthercomprising program instructions to perform at least one of:pre-deploying the first set of nodes; pre-deploying the second set ofnodes; pre-installing a storage tiering service on the first set ofnodes; and pre-installing the storage tiering service on the second setof nodes.
 12. The computer program product of claim 11, whereinactivating the pre-deployed resources according to the disaster recoverypolicy comprises program instructions to perform: automatically addingthe first set of nodes to at least one existing node group;automatically restoring a name-space with respect to the first storagesystem; and initiating restoration of the first set of data.
 13. Thecomputer program product of claim 11, wherein activating thepre-deployed resources according to the disaster recovery policycomprises program instructions to perform automatically adding thesecond set of nodes to at least one existing node group.
 14. Thecomputer program product of claim 11, wherein the pre-deployed resourcescomprise: network bandwidth sufficient to meet a maximum data recoverytime threshold; at least one load balancer sufficient to meet themaximum data recovery time threshold; a first storage tiering serviceinstalled on the first set of nodes; and a second storage tieringservice installed on the second set of nodes.
 15. A computer systemcomprising: one or more computer processors; one or morecomputer-readable storage media; program instructions stored on thecomputer-readable storage media for execution by at least one of the oneor more processors, the program instructions comprising instructions toperform: receiving a disaster recovery policy with respect to a firststorage system, wherein the disaster recovery policy comprises thefollowing information: (i) identification of a first set of nodes thatare available to be used by a gateway in a disaster recovery mode; and(ii) identification of a second set of nodes that are available to beused in a recall storm mode; pre-deploying resources according to thedisaster recovery policy, to provide pre-deployed resources; receivinginformation indicative of a disaster recovery situation with respect toa first set of data stored on the first storage system; and activatingthe pre-deployed resources according to the disaster recovery policy.16. The computer system of claim 15, further comprising programinstruction to perform: monitoring the first storage system with respectto a configuration thereof; determining that the first storage systemunderwent a configuration change; and in response to determining thatthe first storage system underwent the configuration change,automatically adjusting the disaster recovery policy in accordance withthe configuration change.
 17. (canceled)
 18. The computer system ofclaim 15, further comprising program instructions to perform at leastone of: pre-deploying the first set of nodes; pre-deploying the secondset of nodes; pre-installing a storage tiering service on the first setof nodes; and pre-installing the storage tiering service on the secondset of nodes.
 19. The computer system of claim 18, wherein activatingthe pre-deployed resources according to the disaster recovery policycomprises program instructions to perform: automatically adding thefirst set of nodes to at least one existing node group; automaticallyrestoring a name-space with respect to the first storage system; andinitiating restoration of the first set of data.
 20. The computer systemof claim 18, wherein activating the pre-deployed resources according tothe disaster recovery policy comprises program instructions to performautomatically adding the second set of nodes to at least one existingnode group.